SQUREL at TSAR 2025 Shared Task CEFR-Controlled Text Simplification with Prompting and Reinforcement Fine-Tuning

AbstractThis paper summarises the submissions of our team to the TSAR 2025 Shared Task on Readability-Controlled Text Simplification, which aims to create text simplifications balancing reduced linguistic complexity, meaning preservation, and fluency while meeting predefined target readability levels. We tested two different methods for CEFR-controlled simplification a conservative lexical pipeline relying on prompting LLMs to simplify sentences, and a setup employing reinforcement fine-tuning.